How do the singing skills of the main actors in musicals compare with those of popular idol singers?

I think the success of musical actors can't be compared with that of popular idol singers, because although they all sing, they are not in the same field. The songs of pop idols are the main ones. It is within the entertainment scope, so even if they are not particularly climax, as long as they are beautiful enough, then it is ok. Opera singers, on the other hand, simply follow the artistic accomplishment. They don't care about the singer's appearance, but they must pay attention to the singer's skills. So comparing these two, I still feel that each has its own spring and autumn.